This application claims the benefit of Korean Application No. 2002-1886, filed Jan. 12, 2002, in the Korean Industrial Property Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a liquid image developing system, and more particularly, to a liquid image developing system having a simplified structure using a high-concentration developer.
2. Description of the Related Art
In general, liquid image developing systems form an electrostatic latent image corresponding to a desired image by scanning light on a photosensitive body, developing the electrostatic latent image using a developer in which powder-shaped toner is mixed with a liquid solvent, and printing the developed electrostatic latent image on a paper.
FIG. 1 is an example of a conventional image developing system, disclosed in U.S. Pat. No. 5,255,058. As shown in FIG. 1, the conventional image developing system includes a photoconductive drum 10 charged at a predetermined voltage by a photoconductor charging apparatus 14, and an imaging apparatus 16 (i.e., a laser scanning apparatus) to form an electrostatic latent image of a desired image by scanning light onto the charged photoconductive drum 10 and creating a relative voltage difference. The image developing system also includes a developer supplying unit to develop the electrostatic latent image by supplying a developer to the photoconductive drum 10, and an intermediate transfer member 30 to transfer the developed image onto the photoconductive drum 10 and print the transferred image onto a paper 72.
The developer supplying unit prepares the developer with a toner concentration of less than 3% solid and supplies the developer between the photoconductive drum 10 and a development roller 38. For this purpose, the developer supplying unit includes concentration cartridges 82 and 84 containing a concentrated developer with a toner concentration of 25% solid, a solvent cartridge 86 containing pure solvent, and toner reservoirs 55, 57, 59, and 61 to mix the concentrated developer from the concentration cartridges 82 and 84 with the solvent from the solvent cartridge 86 and preparing a developer with a uniform concentration of about 2-3% solid. The developer supplying unit further includes a multicolor liquid developer spray assembly 20 to pump the developing solvent prepared in the toner reservoirs 55, 57, 59, and 61 to pumps 90, 92, 94, and 96, respectively, and to supply the developer to the development roller 38, and a collecting unit to collect excess developer left after the electrostatic latent image is developed. In addition, the collecting unit includes a collection container 50 to collect the developer supplied between the development roller 38 and the photoconductive drum 10 and to return the developer to the toner reservoirs 55, 57, 59, and 61 for each color, and a squeeze roller 26 to impress the photoconductive drum 10 on which the image is developed, and to squeeze the solvent contained in the developed image. The collecting unit further includes a separator 66 to collect the squeezed developer through the collection container 50, to separate color toner from the collection container 50 and to return the solvent to a solvent reservoir 65.
In the above structure, in order to perform a development operation, a developer having four colors, such as yellow (Y), magenta (M), cyan (C), and black (K), with a toner concentration of about 2-3% solid, is provided in the toner reservoirs 55, 57, 59, and 61. Of course, in the case of a system developing a single color, such as black, only one developer is required. In order to prepare a developer for each color, the developer supplying unit fabricates a developer with a corresponding concentration by supplying the concentrated developer and the pure solvent from the concentration cartridges 82 and 84 and the solvent cartridge 86 to the toner reservoirs 55, 57, 59, and 61, respectively. For this purpose, each of the toner reservoirs 55, 57, 59, and 61 measures the concentration of the developer that is mixed according to a concentration sensor (not shown). Likewise, when the developer is prepared, the development operation begins. First, the photoconductor charging apparatus 14 charges the photoconductive drum 10 to a predetermined potential. In this state, the imaging apparatus 16 scans light on the charged photoconductive drum 10 to form an electrostatic latent image of a desired image. Subsequently, the pumps 90, 92, 94, and 96 operate such that the developer provided in the toner reservoirs 55, 57, 59, and 61 is supplied between the development roller 38 and the photoconductive drum 10 through the multicolor liquid developer spray assembly 20, thereby forming the electrostatic latent image. The developed image is transferred to the intermediate transfer member 30 and is printed directly onto the paper 72 if the developed image is formed of only one color. However, if a color image is implemented by overlapping a developer having a plurality of colors, the charge, exposure, and development operations are repeated for each of the colors. For example, if there are four colors, such as yellow (Y), magenta (M), cyan (C), and black (K), the developed image for each color is overlapped on the intermediate transfer member 30. The overlapped color image is printed onto the paper 72 passing through a space between the intermediate transfer member 30 and an impression roller 71.
However, the structure of the system in the operations from preparing the developer to supply and collect the developer is considerably complicated. For this reason, a concentrated high-concentration developer cannot be directly used in the development operation, and instead a low-concentration developer (less than 3% solid) is used in the development operation. If the developer with a low concentration is used, mobility is improved, and thus a difference in density of toner throughout the image is reduced. However, as described above, the concentrated developer and solvent in each of the cartridges 82, 84, and 86, are sent to the toner reservoirs 55, 57, 59, and 61, and mixed with a developer with the low concentration, and thus an electrostatic latent image is developed having the developer with a low concentration. Then, the solvent contained in the developed image is squeezed and collected so that the developer has a high concentration suitable for printing. To make things worse, the size and cost of embedded devices further amplify the problems of this complicated structure.
Thus, in order to solve these problems, a new image developing system is required.
Accordingly, it is an object of the present invention to provide a liquid image developing system having an improved structure in which a high-concentration developer is smoothly used in a development operation without requiring squeezing.
Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
The foregoing and other objects of the present invention are achieved by providing a liquid image developing system, including a development container to store a developer having a charge; a photosensitive body; a development roller partially soaked in the developer in the development container and to rotate to form a development nip with the photosensitive body; a depositing portion to attach the developer to a surface of the development roller; a metering portion to regulate the developer attached to the development roller at a uniform thickness at a first end of the development nip; and a cleaning portion to clean the surface of the development roller at a second end of the development nip; wherein the cleaning portion includes an electrical cleaning member which contacts the development roller and removes the developer attached to the surface of the development roller by an electrical attractive force, and a mechanical cleaning member which contacts the development roller and mechanically cleans the developer attached to the surface of the development roller.